The didactic literature, moral and scientific, of the Middle Ages is abundant, and possesses much curious interest, but it is seldom original in substance, and seldom valuable from the point of view of literary style. In great part it is translated or derived from Latin sources. The writers were often clerks or laymen who had turned from the vanities of youth--fabliau or romance--and now aimed at edification or instruction. Science in the hands of the clergy must needs be spiritualised and moralised; there were sermons to be found in stones, pious allegories in beast and bird; mystic meanings in the alphabet, in grammar, in the chase, in the tourney, in the game of chess. Ovid and Virgil were sanctified to religious uses. The earliest versified Bestiary, which is also a Volucrary, a Herbary, and a Lapidary, that of Philippe de Thaon (before 1135), is versified from the Latin _Physiologus_, itself a translation from the work of an Alexandrian Greek of the second century. In its symbolic zoology the lion and the pelican are emblems of Christ; the unicorn is God; the crocodile is the devil; the stones "turrobolen," which blaze when they approach each other, are representative of man and woman. A _Bestiaire d'Amour_ was written by Richard de Fournival, in which the emblems serve for the interpretation of human love. A Lapidary, with a medical--not a moral--purpose, by Marbode, Bishop of Rennes, was translated more than once into French, and had, indeed, an European fame. Bestiaries and Lapidaries form parts of the vast encyclopaedias, numerous in the thirteenth century, which were known by such names as _Image du Monde_, _Mappe-monde_, _Miroir du Monde_. Of these encyclopaedias, the only one which has a literary interest is the _Tresor_ (1265), by Dante's master, Brunetto Latini, who wrote in French in preference to his native Italian. In it science escapes not wholly from fantasy and myth, but at least from the allegorising spirit; his ethics and rhetoric are derived from Latin originals; his politics are his own. The _Somme des Vices et des Vertus_, compiled in 1279 by Friar Lorens, is a well-composed _tresor_ of religion and morals. Part of its contents has become familiar to us through the Canterbury discourse of Chaucer's parson. The moral experience of a man of the world is summed up in the prose treatise on "The Four Ages of Man," by Philippe de Novare, chancellor of Cyprus. With this edifying work may be grouped the so-called _Chastiements_, counsels on education and conduct, designed for readers in general or for some special class--women, children, persons of knightly or of humble rank; studies of the virtues of chivalry, the rules of courtesy and of manners.[1] Other writings, the _Etats du Monde_, present a view of the various classes of society from a standpoint ethical, religious, or satirical, with warnings and exhortations, which commonly conclude with a vision of the last judgment and the pains of hell.